1. Field of the Invention
The invention relates to an improved structure of a trigger of a nailing machine, and more particularly, for exactly reaching the single-firing effect.
2. Description of the Related Art
Nailing machines can be very dangerous tools. The operation thereof must be very careful in order not to injure persons around the working place. As shown in FIGS. 7 and 8, the trigger mechanism 20 of a conventional nailing machine 10 includes a trigger 21, a torsion spring 22, a slide piece 23 and a spring 24. Under normal operation, a safety lever 12 at the front end of gun mouth 11 has to be compressed against a workpiece (not shown) for shifting the safety lever 12 inwardly and, therefore, the other end 13 thereof is pressed against the torsion spring 22 to be shifted backwards. At that time, the other end 221 of the torsion spring 22 presses the slide piece 23 to be shifted downwardly (see FIG. 9). When the slide piece 23 is moved downwards, a position difference is created between a deep hole 231 adjacent to the middle part of the slide piece 23 and a firing pin 14. By pressing down the trigger 21, a single-firing effect is reached. Under the precondition that the safety lever 12 is not moved inwardly, the firing pin 14 can extend into the deep hole 231 of the slide piece 23 (see FIG. 11) when the operator presses down the trigger 21. Therefore, the safety effect to prevent from firing is reached.
Referring to FIG. 10, the trigger is in a compressed state after firing. If the operator unintentionally cause the safety lever 12 to be in contact with any object, an unexpected nailing effect is also created since the slide piece 23 is situated in the compressed state, too. In other words, the spring 24 can""t move the slide piece 23 upwardly to the safety position due to the continuous frictional relationship between the slide piece 23 and the firing pin 14, thereby leading to tremendous operational danger.
It is a primary object of the present invention to remove the above-mentioned drawbacks and to provide a safer trigger mechanism. After completion of an expected single firing operation, the contact piece touching the firing pin can be automatically removed from or spring away from the safety level. Under the precondition that the trigger is not released in place, the next firing operation is disabled no matter which object the safety lever touches, unless the trigger is released in place according to standard operational procedure.